This one kind of irritates me, mainly because I put quite a bit of time into the first game before basically finding out that it would probably be best to skip it and start with Armored Princess. Luckily I hadn't made it very far before Crossworlds came out, so starting over again didn't hurt too much.
So far I'm glad I switched, as they've streamlined things a bit as far as unit abilities and character development go. You now start the game with two reserve army slots, where before you had to spend runes in the mind tree to buy that ability. This may not seem like much, but having two extra slots to swap armies in and out really does help. It's very easy to lose in this game, that is if you aren't really paying attention to your troops on the battle field. Using tactics is a necessity, if nothing more than to minimize losses. The size of the army you field is tied to the amount of leadership you have, and in the beginning you don't have much. With Crossworlds I've found that using smaller numbers of tougher troops, namely the new orc units you can hire almost right outside of the first town.
He does have a limited amount, however, and pretty soon I had used up all of the standard run of the mill orc warriors. By that time I had cleared out many areas of the map, had obtained a sea chart which enabled travel to another island, and obtained several new spots to recruit troops. I managed to luck across a pair of snakes boots; an artifact that adds to initiative, movement, and attack of all snakes in my army. Luckily I had run into a local villager who had a nasty problem with snakes in his basement, and after clearing them out was able to hire them into my army. Royal Snakes are pretty nasty to begin with, being that they can attack without retaliation. When you add in the bonus from the boots, they can be downright deadly. At least I hope so, because as it stands now I don't have nearly enough leadership to hire as many as I'd like.
I'm sure Crossworlds will get more play time, as the HOMM feel is definitely there. The only difference here is you aren't building up cities, but your hero instead. I've started a Warrior, which from what I can tell is the easiest class due to the leadership bonus and increased rage generation. Speaking of which, they've opted to drop the rage chest from the first in favor of a pet dragon. He's certainly not intimidating, but does get the job done. I'm not sure if I'm going to miss having 4 different rage spirits or not, guess we'll see. So far it seems that the abilities you get for the dragon are more focused and powerful, so that's a big plus.